Within the past decades the prevalence of obesity has risen in virtually all ethnic, racial and socioeconomic populations, in both genders and in all age groups. Obesity is associated with a significantly elevated risk for type 2 diabetes, coronary heart diseases, hypertension and numerous other major illnesses and overall mortality from all causes. Therefore, weight reduction is critical for the obese patient. Thus there is impetus for creating new and alternative treatments for management of obesity.
Tesofensine, i.e. [(1R,2R,3S,5S)-3-(3,4-dichlorophenyl)-2-(ethoxymethyl)-8-methyl-8-azabicyclo[3.2.1]octane], first described in WO 97/30997, is a triple monoamine reuptake inhibitor in development for the treatment of obesity.
Tesofensine effectively produces a weight loss in obese individuals of about twice of that seen with currently marketed anti-obesity drugs. Results from clinical studies with Tesofensine also showed that the compound has a good safety profile and is well tolerated. However, though no clinically relevant cardiovascular adverse events or changes in either blood pressure or pulse were seen, some cardiovascular effects were measured with slight increases in heart rate and trends in blood pressure. Although such small effects have no immediate risk to the patient, some medical and regulatory concerns have been raised based on observational studies, that even small changes in cardiovascular parameters may have long term implications on patients' benefit/risk evaluation.
Preclinical and clinical data suggest that appetite suppression is an important mechanism by which Tesofensine exerts its robust weight reducing effect. Notably, the strong hypophagic response (i.e. less appetite, decreased feeding) to Tesofensine treatment is demonstrated to be linked to central stimulation of noradrenergic and dopaminergic neurotransmission. However, the sympathomimetic mode of action of Tesofensine may also associate with the elevated heart rate and blood pressure observed in clinical settings.
Beta blockers, (β-blockers, beta-adrenergic blocking agents, beta antagonists, beta-adrenergic antagonists, beta-adrenoreceptor antagonists, or beta adrenergic receptor antagonists) are a class of drugs that are typically used for the management of cardiac arrhythmias, protecting the heart from a second heart attack (myocardial infarction) after a first heart attack (secondary prevention), and, in certain cases, hypertension. Beta blockers are also well known for their reductive effect on heart rate.
Metoprolol, i.e. 1-(Isopropylamino)-3-[4-(2-methoxyethyl)-phenoxy]-propan-2-ol, branded under various trade names, is a selective β1 (adrenergic) receptor blocker normally used in the treatment of various disorders of the cardiovascular system, and in particular hypertension.
Carvedilol ((±)-[3-(9H-carbazol-4-yloxy)-2-hydroxypropyl][2-(2-methoxyphenoxy)ethyl]amine) is a mixed, i.e. nonselective alpha and beta blocker. It is marketed under various trade names and is traditionally used in the treatment of mild to severe congestive heart failure (CHF) and high blood pressure.
WO 2013/120935 describes treatment of obesity by co-administration of tesofensine and metoprolol in order to ameliorate drug-induced elevation of blood pressure or increase in heart rate.
The serum half-life of tesofensine is nine days (Bara-Jimenez W, Dimitrova T, Sherzai A, Favit A, Mouradian M M, Chase T N (2004). “Effect of monoamine reuptake inhibitor NS 2330 in advanced Parkinson's disease”. Mov Disord 19 (10): 1183-6.). In comparison, the half-life of beta blockers is quite short with metoprolol in the order of 3-4 hours and carvedilol about 7 to 10 hours. Therefore simultaneous daily administration of these two drugs is likely to induce high fluctuations in the serum levels of the beta blocker and potentially recurrent temporary absence of therapeutic efficacy of the beta blocker.